<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
</head>
<body>
   <ul id="parent">
       <li>hello world</li>
   </ul>
   <button id="btn">btn</button>
    <script>
     var btn=document.getElementById("btn");
     var parent=document.getElementById("parent")
     var li=document.getElementsByTagName("li")[0];
     btn.onclick=function(){
         parent.removeChild(li);
     }
    </script>
</body>
</html>